Additive Manufacturing consists of several processes that produce solid three dimensional (3D) objects from a computer model by building up the object in a layer-by-layer manner. Powder-based Additive Manufacturing processes use powders as the consumable materials, where the powders are deposited and then modified. For example, a layer of powder may be deposited and then modified by selected exposure to electromagnetic radiation, or selected deposition of liquid, which may be followed by exposure to electromagnetic radiation, or electron beam.
One example of a powder-based additive manufacturing process is the selective laser sintering process. In the selective laser sintering process a part is constructed one layer at a time inside a thermally controlled process chamber, which is held a temperature slightly below the melting point of the polymer system being used. A laser beam is raster scanned across the surface of a layer of powder, turning on and off to selectively sinter or fuse the polymer powder particles into a shape defined by a computer which has converted a 3D CAD image into profile slices equal in thickness to the powder layer thickness.
The powder is deposited in thin layers, in the range of approximately 0.05 to 0.30 millimeters deep, uniformly across a piston. After a given layer has been fused, the piston is lowered and a new layer of powder is added on top of the just completed layer. The new layer is then fused, based on the defined shape, and in this manner a three-dimensional object can be fabricated from multiple layers.
In Selective Beam Sintering, the powder is deposited then scanned by a directed energy beam. The energy beam is most commonly a laser but electron beams are also used. In Selective Inhibition Sintering, the powder is deposited, a sintering inhibitor is then selectively deposited, and the powder is then exposed to electromagnetic radiation. In High Speed Sintering, the powder is deposited and then a radiation absorbing liquid is selectively deposited and then the powder is exposed to electromagnetic radiation. In 3D Printing, the powder is deposited and then a binder is selectively deposited. In a mask based process, the powder is deposited and then the powder is exposed to electromagnetic radiation through a mask. In Laser Engineered Net Shaping, the powder is entrained in a gas jet at the same time as the energy beam is applied.